In Long Term Evolution (LTE) Release 8, for Frequency Division Duplexing (FDD) operation, separate uplink and downlink frequency bands are utilized, where the uplink and downlink frequency bands are paired to allow simultaneous transmission in the two frequency bands. The paired uplink and downlink frequency bands have sufficient separation to enable transmitted signals to not unduly impair receiver performance. In LTE Release 10, carrier aggregation is utilized to support bandwidths larger than 20 Megahertz (MHz) while at the same time providing legacy support for LTE Release 8 User Equipment devices (UEs). Specifically, each component carrier has a 20 MHz bandwidth and can be seen by an LTE Release 8 UE as an LTE Release 8 carrier. LTE Release 11 introduces non-contiguous intra-band carrier aggregation.
Carrier aggregation supports simultaneous transmission and reception of multiple carriers from a single UE, which in turn poses serious design challenges. As discussed below in detail, one serious design challenge is UE self-interference wherein an uplink transmission by the UE on an uplink component carrier results in an intermodulation product that falls within a downlink component carrier used by the UE. As such, there is a need for systems and methods for mitigating such self-interference.